An emergency information terminal which is known has emergency information communicating means and is mounted on an automobile or other vehicle, for placing a telephone call to the center supervising the emergency information system such as police or emergency information center through a base station of a communication operator or the like.
For the conventional emergency information terminal, a device for feeding power source into the emergency information terminal by power supply from a main battery or auxiliary battery is proposed. For example, Japanese Laid-open Patent No. 8-287386 discloses power supply from car-mount battery and back-up power source from a large-capacity capacitor. Japanese Laid-open Patent No. 2000-108822 proposes a power supply device feeding from car-mount battery and a power supply device by battery of a cellular phone. The power source control unit of the conventional emergency information terminal inspects the internal circuit of the emergency information terminal periodically and automatically, and informs an user of detection of abnormality in part of the internal circuit. The conventional terminal is operated by the power supply from the power supply circuit in case of emergency, places a telephone call automatically to the emergency information center, and transmits the position information. Then, the position of the vehicle when starting the emergency information process is notified to the emergency information center.
In the conventional emergency information terminal, even if the power source is available in two lines, the power supply circuit is prepared in one line only. Accordingly, if the power supply circuit fails, power supply to the emergency information terminal is cut off, and power supply to the controller for controlling the operation of the terminal is also cut off. As a result, failure of power source cannot be noticed to the user, and emergency call cannot be made in case of emergency.
The conventional emergency information terminal generates a power source for each block in the power source circuit in the terminal, supplies power source to the internal circuit, and also feeds to an external device.
Further, in the conventional emergency information terminal, a power to the inside and a power to external device are supplied from the same power source. Accordingly, in case of drop of supply voltage due to abnormality of consuming a large current such as failure in external device or breakage or short circuit of power supply line, the voltage drops also in the power supply line to the internal circuit connected to the power supply line, and an operation of the emergency information terminal cannot be maintained.